If you find yourself having a strong fear of becoming fat even though you are underweight or have a normal weight, this might signal a problem. Anorexia Nervosa and Bulimia Nervosa are two types of eating disorders that involve disturbed eating patterns and negative thinking related to food. This problem is more common in females than males. It often begins in adolescence and occurs in adulthood.

In Anorexia Nervosa, a person might be so preoccupied with being slim that she/he might starve herself/himself to achieve weight loss. This could have severe consequences and, in women, lead to disturbance in menstrual cycle. The person might be unable to see the seriousness of his problem since such a person tends to have a low body weight.

In Bulimia Nervosa, a person tends to have an inconsistent pattern of eating. Sometimes the person over eats so much that exceeds his/her normal amount (binge-eating) and at other times, the person tries to compensate his over-eating to prevent weight gain by engaging in behaviours such as self-induced vomiting, excessive exercise, fasting or using laxative and diuretics.
The nutritional deficiency caused by eating disorders can have a negative impact on vital organs or have life threatening consequences.